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netfs, cachefiles: Implement helpers for new write code

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Implement the helpers for the new write code in cachefiles.  There's now an
optional ->prepare_write() that allows the filesystem to set the parameters
for the next write, such as maximum size and maximum segment count, and an
->issue_write() that is called to initiate an (asynchronous) write
operation.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-erofs@lists.ozlabs.org
cc: linux-fsdevel@vger.kernel.org
This commit is contained in:
David Howells 2024-03-18 20:31:13 +00:00
parent 5fb70e7275
commit 64e64e6c18
1 changed files with 74 additions and 0 deletions
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74
fs/cachefiles/io.c
View file

@ -9,6 +9,7 @@
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/uio.h>
#include <linux/bio.h>
#include <linux/falloc.h>
#include <linux/sched/mm.h>
#include <trace/events/fscache.h>
@ -622,6 +623,77 @@ static int cachefiles_prepare_write(struct netfs_cache_resources *cres,
return ret;
}
static void cachefiles_prepare_write_subreq(struct netfs_io_subrequest *subreq)
{
struct netfs_io_request *wreq = subreq->rreq;
struct netfs_cache_resources *cres = &wreq->cache_resources;
_enter("W=%x[%x] %llx", wreq->debug_id, subreq->debug_index, subreq->start);
subreq->max_len = ULONG_MAX;
subreq->max_nr_segs = BIO_MAX_VECS;
if (!cachefiles_cres_file(cres)) {
if (!fscache_wait_for_operation(cres, FSCACHE_WANT_WRITE))
return netfs_prepare_write_failed(subreq);
if (!cachefiles_cres_file(cres))
return netfs_prepare_write_failed(subreq);
}
}
static void cachefiles_issue_write(struct netfs_io_subrequest *subreq)
{
struct netfs_io_request *wreq = subreq->rreq;
struct netfs_cache_resources *cres = &wreq->cache_resources;
struct cachefiles_object *object = cachefiles_cres_object(cres);
struct cachefiles_cache *cache = object->volume->cache;
const struct cred *saved_cred;
size_t off, pre, post, len = subreq->len;
loff_t start = subreq->start;
int ret;
_enter("W=%x[%x] %llx-%llx",
wreq->debug_id, subreq->debug_index, start, start + len - 1);
/* We need to start on the cache granularity boundary */
off = start & (CACHEFILES_DIO_BLOCK_SIZE - 1);
if (off) {
pre = CACHEFILES_DIO_BLOCK_SIZE - off;
if (pre >= len) {
netfs_write_subrequest_terminated(subreq, len, false);
return;
}
subreq->transferred += pre;
start += pre;
len -= pre;
iov_iter_advance(&subreq->io_iter, pre);
}
/* We also need to end on the cache granularity boundary */
post = len & (CACHEFILES_DIO_BLOCK_SIZE - 1);
if (post) {
len -= post;
if (len == 0) {
netfs_write_subrequest_terminated(subreq, post, false);
return;
}
iov_iter_truncate(&subreq->io_iter, len);
}
cachefiles_begin_secure(cache, &saved_cred);
ret = __cachefiles_prepare_write(object, cachefiles_cres_file(cres),
&start, &len, len, true);
cachefiles_end_secure(cache, saved_cred);
if (ret < 0) {
netfs_write_subrequest_terminated(subreq, ret, false);
return;
}
cachefiles_write(&subreq->rreq->cache_resources,
subreq->start, &subreq->io_iter,
netfs_write_subrequest_terminated, subreq);
}
/*
* Clean up an operation.
*/
@ -638,8 +710,10 @@ static const struct netfs_cache_ops cachefiles_netfs_cache_ops = {
.end_operation = cachefiles_end_operation,
.read = cachefiles_read,
.write = cachefiles_write,
.issue_write = cachefiles_issue_write,
.prepare_read = cachefiles_prepare_read,
.prepare_write = cachefiles_prepare_write,
.prepare_write_subreq = cachefiles_prepare_write_subreq,
.prepare_ondemand_read = cachefiles_prepare_ondemand_read,
.query_occupancy = cachefiles_query_occupancy,
};